Most Water in Lunar Soil generated by Solar Wind

This is a composite image of the lunar nearside taken by the Lunar Reconnaissance Orbiter in June 2009, note the presence of dark areas of maria on this side of the moon. Credit: NASA

A pair of researchers with the Sorbonne Universités, Muséum National d'Histoire Naturelle, has determined that most of the water in the soil on the surface of the moon was formed due to protons in the solar wind colliding with oxygen in lunar dust, rather than from comet or meteorite impacts.

In their paper published in Proceedings of the National Academy of Sciences, Alice Stephant and François Robert describe their study and the results they found.

When NASA astronauts brought back soil and rock samples from the moon, it was assumed by most in the scientific community that everything they found was dry, that there was no water in any of it.

Subsequent analysis using newer techniques has revealed that not only is there water beneath the surface in some places, but the dust on the surface also has small amounts as well.

Once this became known, most scientists assumed the water got there due to comet or meteorite impacts, in this new effort, the research pair suggests that conventional thinking is wrong once again and that the water, at least in the surface dust, comes about due to the impact of solar wind on tiny dust particles.

In studying tiny grains of lunar soil samples, the researchers found that the reduction of oxygen from silicates in the soil by protons from the solar wind was almost certainly the means by which the water was generated.

They came to that conclusion through determining the lithium isotope ratio in the samples (plagioclase rock found on the surface of the moon) which gave the isotope ratio for the hydrogen, from that they were able to calculate the deuterium-hydrogen ratio which they compared to the amount of water actually in the granule sample.

They found that on average, the granules contained just 15 percent water from somewhere else (presumably comets or meteorites) leaving the rest to have been formed due to the solar wind interaction. They note also that for some samples, all of the water was due to solar wind interaction.

The duo is quick to point out that their conclusions only relate to water found on the surface of the moon, where the water below the surface came from is still up for conjecture.

More information: "The negligible chondritic contribution in the lunar soils water" - Alice Stephant, PNAS, DOI: 10.1073/pnas.1408118111

NASA LRO: Wet or Dry Moon

The Moon's status as a "dry" rock in space has long been questioned. Competing theories abound as to the source of the H20 in the lunar soil, including delivery of water to the Moon by comets.

This week, Tartèse et al announced in Geology that new analyses of lunar soil samples demonstrates that basalts from the Moon's mantle contain hydrogen from water indigenous to Earth.

According to the authors, their work is "challenging the paradigm of a "dry" Moon, and arguing that some portions of the lunar interior are as wet as some regions of the Earth's mantle."


This video from NASA Goddard shows how NASA’s Lunar Reconnaissance Orbiter (LRO) is helping scientists understand where water is likely to exist on the south pole of the Moon. 

Credit: NASA Goddard on YouTube

Since the 1960's, scientists have suspected that frozen water could survive in cold, dark craters at the Moon's poles.

While previous lunar missions have detected hints of water on the Moon, new data from the Lunar Reconnaissance Orbiter (LRO) pinpoints areas near the south pole where water is likely to exist.

The key to this discovery is hydrogen, the main ingredient in water: LRO uses its Lunar Exploration Neutron Detector (LEND), to measure how much hydrogen is trapped within the lunar soil.

By combining years of LEND data, scientists see mounting evidence of hydrogen-rich areas near the Moon's south pole, strongly suggesting the presence of frozen water.

More information: Romain Tartèse, Mahesh Anand, Francis M. McCubbin, Stephen M. Elardo, Charles K. Shearer, and Ian A. Franchi. "Apatites in lunar KREEP basalts: The missing link to understanding the H isotope systematics of the Moon." Geology, G35288.1, first published on February 25, 2014, DOI: 10.1130/G35288.1

Nanoparticles found in moon glass bubbles explain weird lunar soil behaviour

A stunning discovery by Queensland University of Technology (QUT) soil scientist Marek Zbik of nano particles inside bubbles of glass in lunar soil could solve the mystery of why the moon's surface topsoil has many unusual properties.

Dr Zbik, from Queensland University of Technology's Science and Engineering Faculty, said scientists had long observed the strange behaviour of lunar soil but had not taken much notice of the nano and submicron particles found in the soil and their source was unknown.

Dr Zbik took the lunar soil samples to Taiwan where he could study the glass bubbles without breaking them using a new technique for studying nano materials call synchrotron-based nano tomography to look at the particles. Nano tomography is a transmission X-ray microscope which enables 3D images of nano particles to be made.

"We were really surprised at what we found," Dr Zbik said.

"Instead of gas or vapour inside the bubbles, which we would expect to find in such bubbles on Earth, the lunar glass bubbles were filled with a highly porous network of alien-looking glassy particles that span the bubbles' interior.

"It appears that the nano particles are formed inside bubbles of molten rocks when meteorites hit the lunar surface. Then they are released when the glass bubbles are pulverised by the consequent bombardment of meteorites on the moon's surface.

"This continuous pulverising of rocks on the lunar surface and constant mixing develop a type of soil which is unknown on Earth."

Dr Zbik said nano particles behaved according to the laws of quantum physics which were completely different from so called 'normal' physics' laws. Because of this, materials containing nano particles behave strangely according to our current understanding.

"Nano particles are so tiny, it is their size and not what they are made of that accounts for their exceptional properties.

"We don't understand a lot about quantum physics yet but it could be that these nano particles, when liberated from their glass bubble, mix with the other soil constituents and give lunar soil its unusual properties.

"Lunar soil is electro-statically charged so it hovers above the surface; it is extremely chemically active; and it has low thermal conductivity eg it can be 160 degrees above the surface but -40 degrees two metres below the surface.

"It is also very sticky and brittle such that its particles wear the surface off metal and glass."
Dr Zbik said the moon had no atmosphere to cushion the impact of meteorites like Earth had.

"When they hit the moon there is a very violent reaction. Huge temperatures are generated which melts the rock. The pressure goes and a vacuum is created. Bubbles occur in the molten glass rock like soft drink bubbles trying to escape the bottle.

"Our work now is to understand how those particles evolve from this process. It may also lead us to completely different way of manufacturing nanomaterials."

Dr Zbik and his research team's study was published in the International Scholarly Research Network Astronomy and Astrophysics.

To find out more and also view a 3D image from inside the lunar bubble using transmission X-Ray microscopy go to http://youtu.be/omRoS2SntMU. You can see what is inside the lunar bubble with 3D glasses.

Related Links: Queensland University of Technology

Shadow of the Past on the Moon

Surveyor 1, the first of the Surveyor missions to make a successful soft landing, proved the validity of the spacecraft's design and landing technique.

In addition to transmitting more than 11,000 pictures, Surveyor sent information on the bearing strength of the lunar soil, the radar reflectivity and temperature.

This image of Surveyor 1's shadow shows it against the lunar surface in the late lunar afternoon, with the horizon at the upper right. Surveyor 1 was launched on May 30, 1966, and landed on June 2, 1966.

Image Credit: NASA/JPL